New Cascadia w/ Detroit Powertrain will it be good for hauling 80K?

I'd call em small rear ends.
2.xx vs. The older 3.55 which was a majority.

The dd15 500ish with a 13 manual got better economy then the dd13 450ish with 13 manual. Both were same company so the runs were the same.

But having more power I've always gotten better economy.

Autos have low rear ends. Might be great for flat land but that's it. They can't handle dirt for nothing. Any resistance and they stop. You'll need a push. And they suck for beating traffic if you need to make a turn.

The only upside I see is you won't be popping rear ends. They just don't have the juice to make that happen.

 

"Low rears" doesn't mean what you think it does. It's the opposite of what you're thinking. Autos have higher ratios. 2:×× ratio is higher than 3:××. Higher rears are taller. Offroad trucks are geared lower. 4:11 is lower than 3:55, etc...

 

I thought 2 was lower then 3 and gears would be smaller.

 

Sounds like a Roehl spec Shaker. That company tries to spec all their trucks to maximize fuel economy but they are brutally slow and practically die going uphill.

I'll give my current company credit because they run the 500+HP Cummins x15 and have a 3.25 rear end in all their trucks. They chug along perfectly fine and end up getting an average of 6.8mpg, they still get around 5-6mpg near 80k gross driving through a lot of big hill areas like Pennsylvania and Maryland regularly.

 

No, the smaller number is higher ratio, geared higher - faster speeds. Geared low runs slow, "stump puller", etc 4:11, 4:56, 5:14, etc. Highway gears geared high 3:25, 3:08, 2:×× etc.